Method for reinforcing sewn material



32%,390 Patented Jan. 10, 1967 3,296,990 METHQD FUR REHNFQRCHNG SEWN MATERIAL Luther G. Elirnglian, Laurel Laue, Greenwich, Conn. lldtifitl No Brewing. Filed Sept. ll, llidd, her. No. 393,7'7ll l Claims. (Cl. ll2.--2ti2) This invention relates to sewing and particularly to a method for reinforcing stitched material, for instance machinesewn textiles. More specifically, the instant method concerns the reinforcement of material which has been weakened by consecutively spaced stitches and thread penetration.

Modern garments, for instance, are made mostly of material Woven from synthetic fibers, such as Dacron, nylon, Creslan, to name a few. As the trend to thinner and light weight textiles continues, the problem of wealtening the material at the areas of the stitched seams continues to gain greater significance. Particularly in machine-sewing, the needle and thread penetration causes a perforated seam which, in the absence of strong surround ing fibers, is responsible for ready tearing of the garment, principally in the seam.

In order to minimize this occurrence, a process has been devised to provide for the reinforcement of the material at the area heretofore constituting the weakest point, namely the area of thread penetration.

One of the principal objects of this invention is, therefore, the provision of a method for reinforcing thread stitched seams in synthetic materials without substantially affecting the visible appearance of the seam.

Another object of this invention is the provision of a method for reinforcing thread stitches in materials by employing means to soften the material and causing it to flow around the thread at the area of thread penetration.

A further object of this invention is the provision of a method for reinforcing stitched material, using ultrasonic energy which is applied at the points of thread penetration for causing the reinforcement of the stitch.

Further and still other objects of this invention will be readily apparent by reference to the following description of the novel process.

In accordance with the instant process, synthetic textile material is seam stitched with thread in the conventional manner. Subsequently a tool in the form of a rod or tube, is brought into contact with the area at which the thread penetrates the material and ultrasonic energy is applied to the tool. The energy supplied to the tool and dissipated by the material causes the material to soften and to flow, substantially surrounding and adhering to the thread, thus providing reinforcement at this point. It will be apparent that in order to preserve the appearance of the seam, the power level of the ultrasonic energy must be high enough to cause the very localized flow of the material, but must also be low enough so as not to disturb the appearance of the surrounding area as it is a major object of this invention that the pleasing appearance of a stitched seam be preserved.

In the mechanical embodiment of this invention, for machine sewing an oscillating tool is mounted immediately to the rear of the conventional sewing needle on the sewing machine head. The tool is driven to reciprocate in a vertical direction for briefly engaging the material at the area of thread penetration. The tool is coupled to a source of ultrasonic energy, a frequency generally in excess of 16,000 cycles per second. It will be apparent that, if desired, the tool can be controlled to engage only every second, third, or fourth point of thread penetration. Instead of a rod type tool, the preferred embodiment, a tubular tool may be used which is shaped and guided so that the actual point of thread penetration falls into the center of the tube. A radial relief slot may be provided for the thread running to the adjacent stitch.

Alternatively, a rotating star wheel may be used for the tool in order to provide a similar result. However, it will be apperent that whenever the stitch spacing is changed, the star wheel must be changed also.

A further alternative comprises the use of a metallic thread instead of a textile fiber thread. The ultrasonic energy can then be coupled directly to the thread.

It will be apparent that the above described process over comes the weakening of thin synthetic material caused by seam stitching while preserving the appearance of the seam. Furthermore, it will be quite obvious that the process may be applied also to such material as vinyl sheeting which, in the conventional manner, is welded by the use of a rotating wheel. This latter method does not provide the more finished and pleasing appearance which is associated with a stitched seam.

While there has been described a typical and preferred embodiment of the present invention and several alternative constructions, it will readily be apparent to those skilled in the art that various further changes and modifications may be made without deviating from the instant and broad principles of this invention which shall be limited only by the scope of the appended claims.

What is claimed is:

1. A method for reinforcing sewn material in which a thread penetrates the material comprising the steps of: applying a tool at the area of thread penetration, and subjecting said area by means of said tool to ultrasonic energy of a power level sufiicient to cause the dissipated energy to soften the material and flow around the thread. thread.

2. A method for reinforcing sewn synthetic material in which a thread penetrates the material comprising the steps of: applying a tool at the area of thread penetration, and subjecting said area by means of said tool to ultrasonic ener y of a power lever suflicient to soften the material and flow around the thread without substantially atfectin g the appearance or" the stitch.

3. A method for reinforcing a stitched scam in synthetic fiber material involving consecutive points of thread penetration comprising the steps of: applying a tool to at least some of the points of thread penetration, applying ultrasonic energy to said tool and thereby to said points, the power level of said energy being sufiiciently high to cause a slight softening of the material in the immediate proximity to the area of thread penetration, and whereby the material is caused to flow and reinforce the respective area, and being sufficiently low to leave the appearance of the seam substantially undisturbed.

4. A method for reinforcing sewn synthetic material in which a thread penetrates the material comprising the steps of: sewing the material with a metallic thread, and applying ultrasonic energy to the thread, said energy being of a power level to cause softening of the material in the immediate proximity to the thread and its flowing around the thread provides increased strength of the sewn area.

References Cited by the Examiner UNITED STATES PATENTS 3,184,353 5/1965 Balamuth et al. 156-73 PATRICK D. LAWSON, Primary Examiner.

RICHARD J. SCANLAN, 111., Assistant Examiner. 

1. A METHOD FOR REINFORCING SEWN MATERIAL IN WHICH A THREAD PENETRATES THE MATERIAL COMPRISING THE STEPS OF: APPLYING A TOOL AT THE AREA OF THREAD PENETRATION, AND SUBJECTING SAID AREA BY MEANS OF SAID TOOL TO ULTRASONIC ENERGY OF A POWER LEVEL SUFFICIENT TO CAUSE THE DISSIPATED ENERGY TO SOFTEN THE MATERIAL AND FLOW AROUND THE THREAD. THREAD. 